Aside from filling the gas tank, changing a Morgan’s engine oil is perhaps the most common task required to keep the car running properly. This bit of routine maintenance can be done by a ‘quick lube’ shop on your break, at the Morgan dealership (if you have one!) or more commonly, in your own garage or driveway. New, clean oil is an engine’s best friend, but too much of it can cause costly damage, reduce engine performance and should be removed as soon as possible.
If Some Oil is Good, More Oil Must be Better? Right?
To understand how overfilling your engine oil is too much of a good thing, it’s helpful to first provide a little background.
Engines are comprised of hundreds of precision-crafted parts working in unison at high speeds and temperatures, all of which require oil for proper lubrication and smooth movement. You add oil to an engine to the crankcase, as directed by your Morgan’s Owner Handbook, using the oil filler port under the bonnet. The oil settles in the oil pan when the engine is not running. When you start the Morgan, the oil circulates throughout the engine, to lubricate all the moving parts (like the spinning crankshaft), and passes through an oil filter that removes contaminants that could potentially cause damage.
When too much oil is added, the level in the oil pan becomes too high. That allows the spinning crankshaft to come into contact with the oil and essentially aerate it. The result is a foamy, frothy substance that cannot adequately lubricate the engine.
Also, the extra oil may create excessive pressure inside your engine that will look for an escape through various gaskets and seals. If one or more of those fail, that will lead to leaks and who wants a leaky Morgan?
One area that is sometimes omitted when discussing excessive oil is the a drop in engine performance. This drop in performance comes from a few places. The foamy, frothy substance that circulates with the crankshaft weighs something and this added weight makes it harder for the engine to spin. The spinning is what makes the power and adding any load here causes a performance hit. Also, the inconsistency of the oil pressure, caused by the foamy, frothy oil cloud, will most likely result in another performance hit.
Checking to See if Your Morgan Has Too Much Oil
If you think you have excess oil in your Morgan’s engine, the quickest way to know is to look at the dipstick. “Too much oil,” however, is not a precise measurement. Every engine design has different dimensions, so knowing at what level your engine oil will become a foamy, frothy oil cloud is almost impossible.
The dipstick is a graduated rod that slides into a tube that goes into the engine’s oil sump. It typically has low and high marks to show if your car has too much, too little, or the perfect amount of oil. Anywhere in that range is perfectly fine, as is maybe a modest amount above the top level, but I would certainly get nervous going much above that. It’s advisable to get into the habit of checking the level frequently, and certainly after an oil change.
Your owner’s manual can tell what to look for when checking your car’s oil, but the owner’s manual is really only valid if the engine is bone stock. If you have modified the engine’s sump or the engine itself, the manual might be incorrect.
[Note: I once bought a Morgan that didn’t have a dipstick! I went to check the oil and was gobsmacked! (Is that even a word?) So, I know there are universal ones available, and cheap too! Mark]
There are other indicators that will suggest you have an overfill problem, including blue exhaust smoke, a burning smell, an oil leak, or an excessively high or low reading on your oil pressure gauge (some Morgans have gauges, some do not).
What do I do to Get Rid of the Excess?
If you have significantly more oil than the top of the dipstick range, play it safe and let some out. There’s nothing high-tech about the procedure: Loosen the drain plug like you do for an oil change and let out a cup or two at a time. Then snug the drain plug, start and idle your engine for a minute, shut it down, and then recheck the dipstick, wiping it once and then putting it back in for a correct reading. And, do all of this while parked on a level surface. (Make sure you dispose of the used oil properly and don’t just dump it down the drain!)
Also, remember that if you’ve been driving the car before the oil change, the oil is likely hot and could cause burns if you don’t handle it appropriately. If you’d prefer having a ‘quick lube’ do the job, go for it, but be inquisitive and don’t just assume they know what they are doing. Make sure they do it correctly and check their work afterwards. They may know Toyotas but will not be familiar with Morgans.